As the number of electric cars on world roads grows, how drivers pay for electricity from public charging stations may become more of an issue.

While many U.S. public charging stations are free to use today, that may not always be the case in future.

And questions of electricity use have already caused friction between some car owners and other users of shared facilities like condominiums.

ALSO SEE: Judge 'Charged' With 'Theft' For Plugging In Chevy Volt Electric Car (Oct 2012)

Now, a German company is bringing a device to market that could provide more clarity on how much electricity is used--and who pays for it.

Ubitiricity markets a charging cord that can be plugged into standard electrical outlets, with software that allows for remote billing, according to Forbes.

Using the cord, drivers can plug into most any socket to charge. Ubitricity monitors charging and reimburses any people or entities that may host these charging sessions.

Ubitricity electric-car charging cord

Ubitricity electric-car charging cord

The system is designed to let electric-car drivers take better advantage of existing electricity infrastructure without the risk of appearing to steal power paid for by others.

Ubitricity argues that its approach--which essentially turns a charging cord and smartphone into a mobile electricity meter--will be easier to implement on a large scale than building dedicated charging stations.

It could also make for greater flexibility, by allowing drivers to charge for short periods of time in areas where a permanent charging station might not be practical.

DON'T MISS: Germany Mulls Boosting Electric-Car Incentives Under Carbon-Goal Pressure

The company is considering installing 3.7-kilowatt charging sockets in light posts.

It claims these sockets would cost just 300 euros ($327), compared to 10,000 euros ($10,912) for standalone charging stations.

Ubitricty notes that some drivers may still want DC fast charging or conventional charging at more than 3.7 kW, but claims its system will be adequate for most people, most of the time.

Ubitricity electric-car charging cord

Ubitricity electric-car charging cord

It even believes that utilities could market mobile electricity subscription services--almost like cellphone plans--using the charging units to record how much electricity is being used.

Theoretically, a customer would pay to have access to a utility's electricity anywhere and everywhere, carrying around a "mobile meter" rather than relying solely on the ones at their homes.

MORE: Is BMW i3 Electric Car Selling Better In U.S. Than Germany?

Before any of that can happen, though, Ubitricity has to get its charge cord ready for mass production.

The company has been running a pilot program with 25 cars, and plans to launch a "final prototype generation" sometime in the next couple of months.

[hat tip: Michael Soremekun]


Follow GreenCarReports on Facebook, Twitter, and Google+.